The Olive-sided Flycatcher can be identified by several field marks.
Males and females cannot be differentiated by plumage. Look for Olive-sided Flycatchers on sitting on prominent branches of conifers or snags (standing dead trees), surveying for insects or vocalizing.
You are more likely to hear an Olive-sided Flycatcher before you see it. Only males sing but both males and females give calls.
Male Olive-sided Flycatchers sing to establish and defend their territories, and to attract a mate. Their song is a series of three whistled notes that descends slightly on the last note which sounds like “Quick, three beers!” . The song is loud and can be heard from well over 100 metres away.
Males and females use calls to communicate with each other and fend off aggressive neighbours who encroach on their territory. This call is an evenly spaced “pip pip pip.”